Large chunks of the Perito Moreno glacier in the country's National Park Los Glaciares began sliding off nearly seven days ago. As the breaks began to occur, tourists gathered on large platforms to witness the phenomenon.

Those who stayed amid the dark clouds and storm were rewarded with seeing a spectacle of nature that first occurred in 1917 and has only happened two times since. The last time such a collapse occurred was nearly four years ago, in July 2008.

The Perito Moreno glacier is located near the city of El Calafate in the Patagonian province of Santa Cruz, in the southern end of Argentina.

The glacier, which covers 97 square miles, flows nearly two miles per day into a lake known as Lago Argentino. As it flows, the glacier cuts off the lake's feeder river and creates an ice dam.

Water pressure then builds behind the dam and eventually breaks the ice wall, as it did Sunday.

The fracture of the glacier might last two or three full days, according to travel experts.